North Korean leader Kim Jong-un is on a trip to China for talks with Chinese President Xi Jinping, state media reported Tuesday, a development that could suggest a second summit between Kim and U.S. President Donald Trump is forthcoming.

Kim and his wife Ri Sol-ju left for China Monday afternoon for a four-day visit at the invitation of the Chinese president, Pyongyang's Korean Central News Agency said. China's Xinhua news agency also confirmed his visit.

The confirmation of Kim's trip to China came after South Korean media reports said earlier that a special train carrying a high-ranking North Korean official crossed into China on Monday night.

It was Kim's fourth trip to the neighboring ally and came as Washington and Pyongyang are in talks to set the venue for a meeting between Kim and Trump.

Kim is widely expected to discuss with Xi his possible second summit with Trump.

Last year, Kim traveled to China and met with Xi three times before and after he held his first-ever summit with Trump in June in Singapore.

In the Singapore summit, Kim agreed to work toward complete denuclearization of the Korean Peninsula in exchange for security guarantees and new relations with the U.S.

Progress, however, has been slow in denuclearization for months as the North calls for sanctions relief, while Washington says such concessions would not be granted until the North completely gives up its nuclear weapons.

In his New Year's speech last week, the North's leader warned that he could take a new way if the U.S. clings to pressure and sanctions on its regime. He still kept the door open for talks with the U.S., saying he is willing to meet Trump at any time.

Trump earlier said that the U.S. and North Korea are in talks over where to hold their second summit, adding that the decision on the venue will be announced in the "not-too-distant future." (yonhap)